clear all;
close all;
clc;

H = 19100e3;
Rz = 6400e3;
Tobr = 12*60*60;
Tmod = Tobr / 2;
wobr = 2*pi / Tobr;
c_light = 3e8;
f_0 = 1602e6;

dt = 5 * 60;
t = 0:dt:Tmod;

rr = [0; Rz];

rsv = (H + Rz) * ...
        [cos(wobr*t);
         sin(wobr*t)];

rv = rsv - repmat(rr, 1, length(t));
D = sqrt(rv(1,:).^2 + rv(2,:).^2);
ind = find(rv(2,:) > 0);
V = diff(D)/dt;
df = - V/c_light *f_0;

figure;
subplot(2,1,1)
plot(t(2:end), df, t(ind), df(ind-1));
xlabel('t,sec')
ylabel('\Delta f, Hz')

subplot(2,1,2)
hist(df,10);


